package cn.ecut.dao;

import com.mysql.fabric.xmlrpc.base.Param;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/**
 * @Author ruanxin
 * 操作数据库的公共类
 */
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    //静态代码块类加载时就初始化
    static {
        Properties properties = new Properties();
        //通过类加载器加载对应资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");

        try {
            properties.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");
    }

    //获取数据库链接
    public static Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }

    //编写查询公共类
    public static ResultSet execute(Connection connection, PreparedStatement preparedStatement, ResultSet rs,
                                    String sql, Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i + 1, params[i]);
        }
        rs = preparedStatement.executeQuery();
        return rs;
    }

    //编写增删改公共方法
    public static int execute(Connection connection, PreparedStatement preparedStatement, String sql,
                              Object[] params) throws SQLException {
        int updateRow =0;
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i + 1, params[i]);
        }
        updateRow = preparedStatement.executeUpdate();
        return updateRow;
    }

    //释放资源
    public static boolean close(Connection connection, ResultSet rs, PreparedStatement preparedStatement) {
        boolean flag = true;
        if (rs != null) {
            try {
                rs.close();
                //GC回收
                rs = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        if (preparedStatement != null) {
            try {
                preparedStatement.close();
                //GC回收
                preparedStatement = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        if (connection != null) {
            try {
                connection.close();
                //GC回收
                connection = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        return flag;
    }
}
